Transparent display apparatus

ABSTRACT

A transparent display apparatus is provided that is constructed to transmit or block a light of images selectively according to a supply of electric power to a conventional transparent organic light emitting diode. The transparent display apparatus includes a transparent organic light emitting diode having a glass substrate, a transparent anode, a hole transport layer, an emitting layer, an electron transport layer and a transparent cathode. The transparent display apparatus includes an insulating layer stacked on the transparent cathode, and first and second transparent ITOs stacked on the insulating layer to deliver electromotive force onto an entire surface and to transmit or block the light of images according to the on/off state of a power source. The transparent display apparatus also includes an electro chromic layer provided between the first and the second transparent ITOs and including transparent and colorless chemicals. The electro chromic layer forms a color through oxidation-reduction reaction of the chemicals according to the on/off state of the power source to absorb or block the light of images. The transparent display apparatus further includes a substrate stacked on the second transparent ITO.

PRIORITY

This application claims priority under 35 U.S.C. §119(a) to anapplication entitled “Transparent Display Apparatus” filed in the KoreanIntellectual Property Office on Jun. 27, 2008 and assigned Serial No.10-2008-0061638, the contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a transparent displayapparatus, and more particularly, to a transparent display apparatusconstructed for selectively transmitting or blocking light of an imageaccording to a supply of electric power to a conventional transparentorganic light emitting diode.

2. Description of the Related Art

In general, an organic light emitting display device has a stackstructure of an Organic Light Emitting Diode (OLED) and a Thin FilmTransistor TFT layer. The OLED that emits light is stacked on the TFTlayer forming an electric circuit, so that an emitting layer of the OLEDcan selectively emit light based on a signal controlled through the TFTlayer.

The organic light emitting display device can be divided into an OLEDdisplay apparatus on a non-transparent substrate and a transparent OLEDdisplay apparatus on a transparent substrate. The structure of thetransparent OLED display apparatus is described below.

The display apparatus includes a TFT layer (not shown) having asubstrate, a gate electrode, a source region, a drain region, a viahole, etc.

As shown in FIGS. 1 and 2, the Transparent Organic Light Emitting Diode(TOLED) 1 includes a transparent anode 3, a hole transport layer 4, anemitting layer 5, an electron transport layer 6, and a transparentcathode 7, which are sequentially stacked on a glass substrate 2 of theTFT layer.

When a voltage is applied to the gate electrode, a channel in an organicsemiconductor region is opened and a current flows from the sourceregion to the drain region, which then passes through the transparentanode 3, the hole transport layer 4, the emitting layer 5, the electrontransport layer 6, and the transparent cathode 7 of the TOLED 1 throughthe via hole. A light emitting function (that is, a function resultingfrom the application of an electric current) occurs in the emittinglayer 5, when holes and electrons are combined and excited and theresulting energy is thus emitted in the form of light. This light refersto, for example, an emitting point corresponding to one pixel of adisplay panel.

As shown in FIGS. 1 and 2, the light emitting type can be divided into adownward emitting type in which light is emitted in a substratedirection, and an upward emitting type in which light is emitted in theopposite direction with respect to a light-emitting direction. Currenttrends favor the upward emitting type, in which the light can be emittedover a relatively wider region. The light in the upward emitting typecan be projected out of a wide region through a black-matrix (notshown). The light in the downward emitting type can be projected out ofonly a region corresponding to the gate electrode. The cathode should benaturally transparent so that the light can travel in the upperdirection. To this end, the conventional cathode was made to have astructure where indium-tin oxide (ITO) and silver (Ag) are stacked oneby one.

A metal such as silver (Ag) is thinly laid and a transparent ITO isstacked on the metal in a desirable thickness. Thus, the conductivitycharacteristic of the metal and the light transmittance characteristicof ITO are combined. Here, the silver (Ag) is defined to have athickness of about 5 nm, and the ITO is defined to have a thickness ofabout 50 to 200 nm.

Characteristics of the cathode should include good light transmissionand the maintaining of a certain level of conductivity to prevent anunduly power consumption. Therefore, the cathode includes the ITO andthe silver (that is, a metal) stacked on each other, which have the twoabove-mentioned characteristics.

The conventional TOLED may show its back side simultaneously, and such acharacteristic may be considered as an advantage of the conventionalTOLED. However, such a characteristic may sometimes decrease visibilityor serve as a disturbance because the background can be seen.

When the conventional TOLED is applied to a watch-type mobile terminal,the watch-type mobile terminal always needs to display the time for aphone mode even when not in a communication state. However, when adisplay for the phone mode is adorned like that of a watch, it isnecessary to keep turning on the display screen, which increases thepower consumption of the mobile terminal. Moreover, it is impossible toadorn the watch-type mobile terminal with jewels as for an ordinarywatch.

SUMMARY OF THE INVENTION

The present invention has been made to address at least the aboveproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the present inventionprovides a transparent display apparatus having a construction forselectively transmitting or blocking light of an image according to thesupply of electric power to a conventional TOLED, so that a backgroundscreen can be selectively transmitted or blocked according to the use ofa product.

Another aspect of the present invention provides a transparent displayapparatus having a construction for selectively transmitting or blockinglight of an image according to the supply of electric power to aconventional TOLED, so that an overlaid display of a product can bemanufactured and the display of a front/back side is possible accordingto the supply of electric power, thereby allowing a user to recognizethe front side display of the conventional TOLED and improving the useof a product.

An additional aspect of the present invention provides a transparentdisplay apparatus for reducing power consumption by adjustingtransmission/non-transmission and the degree of the transmissionaccording to the intensity of the supply of electric power, and savingmanufacturing cost since a patterning process of a pixel unit isunnecessary.

A further aspect of the present invention provides a transparent displayapparatus that includes a transmissive-type Liquid Crystal Display (LCD)for transmitting or blocking the light of images selectively accordingto the supply of electric power to a conventional TOLED, so thattransmittance can be adjusted and manufacturing cost also can be savedbecause its panel form does not require a patterning process of a pixelunit, thereby curtailing the time of the assembly process.

An aspect of the present invention also provides a transparent displayapparatus and a transmissive-type LCD applied to a watch-type phone,which selectively transmit or block the light of an image according tothe supply of electric power to a conventional TOLED, thereby reducingthe power consumption of a product because a watch display is possibleeven when there is no supply of electric power, and allowing the use ofimages of a watch.

According to one aspect of the present invention, a transparent displayapparatus is provided having a TOLED. The TOLED includes a glasssubstrate, a transparent anode, a hole transport layer, an emittinglayer, an electron transport layer, and a transparent cathode. Thetransparent display apparatus includes an insulating layer stacked onthe transparent cathode, and first and second transparent ITOs stackedon the insulating layer to deliver electromotive force onto the entiresurface of the apparatus and to transmit or block the light of imagesaccording to the on/off state of a power source. The transparent displayapparatus also includes an electro chromic layer provided between thefirst and the second transparent ITOs, which includes transparent andcolorless chemicals. The electro chromic layer forms a color throughoxidation-reduction reaction of the chemicals according to the on/offstate of a power source to absorb or block the light of images. Thetransparent display apparatus further includes a substrate stacked onthe second transparent ITO.

According to another aspect of the present invention, a transparentdisplay apparatus is provided having a TOLED. The TOLED includes a glasssubstrate, a transparent anode, a hole transport layer, an emittinglayer, an electron transport layer, and a transparent cathode. Thetransparent display apparatus includes an insulating layer stacked onthe transparent cathode, and first and second transparent ITOs stackedon the insulating layer to deliver electromotive force onto the entiresurface of the apparatus and to transmit or block the light of imagesaccording to the on/off state of a power source. The transparent displayapparatus also includes first and second polarizers provided between thefirst and the second transparent ITOs, and a transmissive-type LCDprovided between the first and the second polarizers to transmit orblock the light of images according to the on/off state of the powersource.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following detailed descriptionwhen taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a cross section of the conventionaltransparent display apparatus;

FIG. 2 is a diagram illustrating a cross section and the operation stateof the conventional transparent display apparatus;

FIG. 3 is a diagram illustrating a cross section of a transparentdisplay apparatus according to an embodiment of the present invention;

FIG. 4 is a diagram illustrating a cross section of a transparentdisplay apparatus according to another embodiment of the presentinvention;

FIG. 5 is a diagram illustrating a state of displaying a front sidefirst screen of the operation states of a transparent display apparatusaccording to an embodiment of the present invention; and

FIG. 6 is a diagram illustrating a state of displaying a back sidesecond screen of the operation states of a transparent display apparatusaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the present invention are described in detailwith reference to the accompanying drawings. The same or similarcomponents may be designated by the same or similar reference numeralsalthough they are illustrated in different drawings. Detaileddescriptions of constructions or processes known in the art may beomitted to avoid obscuring the subject matter of the present invention.

It is to be understood that the structure recited and shown in thepresent specification and the drawings is presented as one example forthe best mode for operating the present invention and does not representall of the principles of the present invention, so various modificationsthereof can be made on the application date of the present invention.

As shown in FIG. 3, a transparent display apparatus 10 includes a TOLED1 having a glass substrate 2, a transparent anode 3, a hole transportlayer 4, an emitting layer 5, an electron transport layer 6 and atransparent cathode 7, an insulating layer 11, first and secondtransparent ITOs 12 and 14, an electro chromic layer 13, and a glasssubstrate 15.

As shown in FIG. 3, the insulating layer 11 is stacked on thetransparent cathode 7 to maintain electrical insulation between anelectrode of the electro chromic layer 13 and an electrode of the TOLED1. The first and second transparent ITOs 12 and 14 are stacked on theinsulating layer 11 to deliver electromotive force onto the entiresurface and to transmit or block the light of images in particularaccording to the on/off state of a power source. Further, the electrochromic layer 13 includes transparent and colorless chemicals in a gelstate, and is provided between the first and the second transparent ITOs12 and 14, so as to form a color through oxidation-reduction reaction ofthe chemicals according to the on/off state of a power source, therebyabsorbing or blocking the light of an image. The glass substrate 15 isstacked on the second transparent ITO 14 to protect the first and secondtransparent ITOs 12 and 14 and the electro chromic layer 13.

As shown in FIG. 3, the electro chromic layer 13 includes a sealingapparatus 20 for sealing the gel.

As shown in FIGS. 3, 5 and 6, when a power source (0.4 to 1.6 V dc) isON, the electro chromic layer 13 forms a black color byoxidation-reduction reaction of two kinds of chemicals, so as to blockthe light of background images and simultaneously display a front sidefirst screen 16. When the power source is OFF, it forms a transparentcolor, thereby absorbing and transmitting the light of background imagesand displaying therefore a back side second screen 17.

The electro chromic layer 13 can adjust transmittance by the intensityof the power source.

The structure of a transparent display apparatus according to the firstembodiment of the present invention has been described. The operationprocess of the transparent display apparatus is described in detailbelow with reference to the accompanying FIGS. 3, 5 and 6.

A transparent display apparatus 10 having the above structure is appliedto the watch-type mobile terminal 100.

According to an embodiment of the present invention, the transparentdisplay apparatus 10 is applicable to other electronic devices and allportable communication devices as well as the transparent displayapparatus 10.

As shown in FIG. 5, if the transparent display apparatus 10 is suppliedwith electric power, a voltage of the electro chromic layer 13 turns ON(for example, 0.4 to 1.6 V dc). At the same time, the electro chromiclayer 13 forms a black color by oxidation-reduction reaction of twokinds of chemicals, thereby blocking the light of watch backgroundimages of the watch-type mobile terminal 100.

A phone-mode image of the watch-type mobile terminal 100 is thendisplayed.

Herein, a user can make a phone call through the phone-mode image of thewatch-type mobile terminal 100.

The watch-type mobile terminal 100 has a phone-mode background as afront side first screen 16, and also has a watch background as a backside second screen 17.

As such, the watch-type mobile terminal 100 operates a display of afront side first screen when it is in the phone-mode, and does not showthe watch background of the back side second screen 17.

As shown in FIG. 6, if the transparent display apparatus 10 is notsupplied with electric power, a voltage of the electro chromic layer 13turns OFF. At the same time, the electro chromic layer 13 and the firstand second transparent ITOs 12 and 14 form a transparent color, therebyabsorbing and transmitting the light of watch background images of thewatch-type mobile terminal 100.

The front side first screen 16 of the watch-type mobile terminal 100becomes transparent and the watch background of the back side secondscreen 17 can be shown.

As such, the back side watch background of the watch-type mobileterminal 100 can be displayed without the supply of electric power sothat power consumption of the mobile terminal is reduced and jeweladornment of the screen is practicable, therefore luxury images can bepresented.

The operation process of a transparent display apparatus according toanother embodiment of the present invention will be described in detailwith reference to the accompanying FIGS. 4, 5 and 6.

As shown in FIG. 4, a transparent display apparatus 30 includes a TOLED1, an insulating layer 31, first and second transparent ITOs 32 and 33,first and second polarizers 34 and 35 provided between the first and thesecond transparent ITOs 32 and 33, and a transmissive-type LCD (forexample, a transmissive TN normal white liquid-crystal) 36 providedbetween the first and the second polarizers 34 and 35. The TOLED 1includes a glass substrate 2, a transparent anode 3, a hole transportlayer 4, an emitting layer 5, an electron transport layer 6, and atransparent cathode 7.

A transparent display apparatus 30 having the above structure is appliedto the watch-type mobile terminal 100.

As shown in FIG. 5, if the transparent display apparatus 30 is suppliedwith electric power, the transmissive TN NW LC 36 turns ON and isoperated, thereby blocking the light of watch background images, thatis, the back side second screen of the watch-type mobile terminal 100.

A phone-mode image, that is, the front side first screen 16 of thewatch-type mobile terminal 100 is displayed.

A user can make a phone call through the phone-mode image of thewatch-type mobile terminal 100.

As such, the transmissive-type LCD 36 is operated to function a displayof the front side first screen 16 when the watch-type mobile terminal100 is in the phone-mode, and thus the watch background of the back sidesecond screen 17 is not shown.

As shown in FIG. 6, if the transmissive-type LCD 36 is not supplied withelectric power, the transmissive-type LCD 36 remains transparent,thereby transmitting the light of watch background images, that is, theback side second screen 17 of the watch-type mobile terminal 100.

The front side first screen 16 of the watch-type mobile terminal 100becomes transparent and the watch background of the back side secondscreen 17 can be shown.

Likewise, the back side watch background of the watch-type mobileterminal 100 can be displayed without the supply of electric power sothat power consumption of the mobile terminal is reduced and jeweladornment of the screen is possible, and therefore luxuriant images canbe presented.

While the invention has been shown and described with reference tocertain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and detail may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

What is claimed is:
 1. A transparent display apparatus having atransparent organic light emitting diode, the transparent organic lightemitting diode comprising a glass substrate, a transparent anode, a holetransport layer, an emitting layer, an electron transport layer, and atransparent cathode, the transparent display apparatus comprising: aninsulating layer stacked on the transparent cathode; first and secondtransparent Indium-Tin Oxide (ITO) layers stacked on an upper part ofthe insulating layer to deliver electromotive force onto an entiresurface of the transparent display apparatus and to transmit or blocklight of images according to an on/off state of a power source; anelectro chromic layer disposed between the first and the secondtransparent ITO layers and comprising transparent and colorlesschemicals, wherein the electro chromic layer forms a color through anoxidation-reduction reaction of the chemicals according to the on/offstate of the power source to absorb or block the light of images; and asubstrate stacked on the second transparent ITO, wherein the electrochromic layer forms a black color, so as to block a light and display animage corresponding to a phone-mode on a front side of the transparentdisplay, when the power source is on, and wherein the electro chromiclayer forms a transparent color, so as to transmit the light such that auser can see a watch positioned at a back side of the transparentdisplay, when the power source is off.
 2. The transparent displayapparatus as claimed in claim 1, wherein the electro chromic layercomprises transparent and colorless chemicals in a gel state, and theelectro chromic layer has a sealing apparatus for sealing the gel. 3.The transparent display apparatus as claimed in claim 1, wherein theelectro chromic layer forms a black color through an oxidation-reductionreaction of two kinds of chemicals, so as to block a light of backgroundimages and display a front side first screen, when the power source (0.4to 1.6 V dc) is on, and wherein the electro chromic layer forms atransparent color, so as to absorb and transmit the light of backgroundimages and display a back side second screen, when the power source isoff.
 4. The transparent display apparatus as claimed in claim 3, whereinthe front side first screen of the electro chromic layer is a phone-modebackground of a watch-type phone, and wherein the back side secondscreen is a watch background of the watch-type phone.
 5. The transparentdisplay apparatus as claimed in claim 1, wherein the electro chromiclayer adjusts transmittance through an intensity of the power source. 6.A transparent display apparatus, comprising: a substrate; first andsecond transparent electrode layers stacked on the substrate to deliverelectromotive force onto an entire surface of an electro chromic layerand to transmit or block light of images according to an on/off state ofa power source; the electro chromic layer disposed between the first andthe second transparent electrode layers, wherein light transmittance ofthe electro chromic layer is adjusted according to whether electricalpower is applied to the first and second transparent electrode layers;an insulating layer stacked on an upper part of the second transparentelectrode layer; and a transparent organic light emitting diode layerstacked on the insulating layer, wherein the electro chromic layer formsa black color, so as to block a light and display an image correspondingto a phone-mode on a front side of the transparent display, when thepower source is on, and wherein the electro chromic layer forms atransparent color, so as to transmit the light such that a user can seea watch positioned at a back side of the transparent display, when thepower source is off.
 7. The transparent display apparatus as claimed inclaim 6, wherein the electro chromic layer forms a color to absorb orblock a light according to the applied electrical power.